Moss Hart’s autobiography "Act One" was big news in 1959. But are people interested in a man whose fame on Broadway happened well over a half-century ago?

If they’re not, it’s hard to see what they’ll find to savor — other than a delightful performance by Tony Shalhoub — in James Lapine’s stage adaptation of the book, which opened Thursday night at the Vivian Beaumont Theater.

Lapine, who also directed, obviously has great affection for Hart (a winning Santino Fontana), who rose from a tumultuous, poverty-ridden childhood in the Bronx, with little education, to become a leading playwright, collaborating with George S. Kaufman (Shalhoub) on such classic comedies as "The Man Who Came to Dinner" and "You Can’t Take It With You."

Branching out into directing, Hart famously staged "My Fair Lady," as well as other musicals and plays.

In adapting the autobiography, Lapine seems to have been loath to leave anything out. The 2-hour-45-minute production, which has an epically clumsy, revolving, three-story set, is crammed with such peripheral figures as Hart’s parents’ neighbors, Kaufman’s wife and walk-by famous people, including Harpo Marx, Dorothy Parker and Edna Ferber.

More damaging, Hart himself never comes into strong focus. In his life story, he naturally wrote about the many individuals he encountered. The play, which ends in 1930, with the production of his first hit, "Once in a Lifetime," doesn’t fill in much that’s revealing about the man.

We learn that he was stage-struck from the time his Aunt Kate (an egregiously overacting, but amusing, Andrea Martin) took him to plays, and that he became a smart, talented, hard-working writer. There’s not even a hint of his bipolar disorder or apparently wavering sexual identity.

His unlikely rise to the top is presented as weirdly easy.

He gets a job as an office boy for a producer, writes a play (which fails), encounters another, more famous, producer, who links him with Kaufman, who’s a supportive mentor, and, though the writing of "Once in a Lifetime" is a creative struggle, becomes a success, enabling him to move his mother, father and younger brother to Manhattan.

The second act centers on the difficulties in writing "Once in a Lifetime," which is about a vaudeville trio trying to break into the movies.

Any chance that the creative process might provide drama is eliminated by our being kept on the outside, never being cued on exactly what was wrong or how the two men went about fixing it.

We see an isolated scene that’s in the process of being written, and it’s completely unfunny. (How, we wonder, did the play become a hit?)

Discussing another part of the play, Hart says, "One reason the second act falls flat in the middle is because we are losing May, George and Jerry. We need to give May some vulnerability. Here’s a big idea: Let May have a romantic interest in Jerry."